This invention relates to seals of the type used to seal hasps in enclosures, such as doors of vehicles, merchandise containers, mail bags and the like where the function of the seal is to detect pilferage.
Known seals of this type are formed of a single piece of molded plastic with male and famale fastener portions disposed on opposite ends of an elongated shackle, said fastener portions being adapted for non-separable engagement. A seal of this type is described in U.S. Pat. No. 3,466,077 issued Sept. 9, 1969. This seal has been found to be highly satisfactory in many applications, since to remove the seal, the shackle must be cut, since it is impossible to disengage the interlocking fastener portions without permanent damage thereto. However, it has been found that in situations where personnel must remove hundreds of seals per day to unload the bag contents, the cutting of the seal is time consuming, and the cut seals accumulate on the floor. Some other types of seals used for this purpose are provided with a weakened portion in the shackle, which must be strong enough to resist breaking during normal handling, yet must be weak enough to break readily when tampered with by unauthorized personnel, and to permit rapid removal by authorized personnel. However, it has been found that if the breaking strength is great enough to resist fracture during rough handling, it is great enough to cause sore fingers in the personnel that must open a large number of bags per day.